If $x \triangleleft y = 2x^{2}-y^{2}$ and $x \circledcirc y = 5x-y$, find $(0 \circledcirc 2) \triangleleft -5$.
Explanation: First, find $0 \circledcirc 2$ $ 0 \circledcirc 2 = (5)(0)-2$ $ \hphantom{0 \circledcirc 2} = -2$ Now, find $-2 \triangleleft -5$ $ -2 \triangleleft -5 = 2(-2)^{2}-(-5)^{2}$ $ \hphantom{-2 \triangleleft -5} = -17$.